As I write, Nick Clegg is struggling through his speech to the House of Commons on Lords Reform. The chamber is packed, the heckling loud and persistent and he certainly doesn't look like a man who is about to get his way, which is not surprising; all the signs are that he isn't.
It is always hard to do the maths on these things, but even if some committed Labour reformers cross the floor to support the government tomorrow, it looks as if the Tory rebellion will be signficant enough to kill off the prospect of Lords reform this year and, probably, for a generation.
The question is; what happens then?
The fear in Downing Street is that Nick Clegg will feel he has no choice but to mollify his furious back-benchers by refusing to support the constituency boundary changes when the bill that is set to redraw them returns to the Commons next year.
This is a 'nuclear' issue for the Tories, because they argue that the coalition agreement makes it clear that the Lib Dems' support for these changes (which almost everyone argues would give the Tories more seats and are generally considered vital to their election prospects) was conditional on Tory support for the AV referendum (which was delivered).
In short, the Tories will be in an absolute rage if the boundary changes are ditched. And since Downing Street calculates that, in a straight choice, the country will still probably opt for David Cameron over Ed Miliband, it is not impossible that it might trigger an early general election.